The present invention relates to semiconductor wafer fabricating equipment; and in particular to apparatus for cleaning the semiconductor wafer during fabrication.
Following chemical-mechanical polishing, a semiconductor wafer often is scrubbed with a "pancake" style pad to remove particles of the polishing slurry left on the surface of the semiconductor wafer. Such flat pancake pads are fixed onto a mounting plate with an adhesive and the mounting plate then is attached to a holder by bolts, machine screws or other mechanical fasteners. The pad is part of a wafer cleaning machine which rotates the mounting plate and pad against the major flat surface of the semiconductor wafer being cleaned. The chemicals used to clean semiconductor wafers may break down the adhesive used to attach the scrubbing pad to the mounting plate, resulting in the pad detaching during the scrubbing operation.
Some of the particulate matter being removed from the semiconductor wafer builds up on the pad over the course of repeated scrubbing operations; thereby necessitating periodic replacement of the pad. The procedure of changing conventional cleaning pads is somewhat time consuming requiring unbolting of the mounting plate from the cleaning machine and stripping the adhesively applied pad from the mounting plate. The scrubbing machine is taken out of operation, during the pad replacement procedure. In addition, use of adhesives to attach the pad can contaminate the cleaning machine, the clean room in which the wafer cleaning occurs and nearby semiconductor wafers.
Therefore, it is desirable to have a semiconductor wafer cleaning tool which resists the build up of particles on its surfaces. It is also desirable to enable easy replacement of the cleaning tool without dismantling the cleaning machinery and without using adhesives and other materials which could contaminate the clean room environment.
Furthermore, conventional pancake style scrubbing pads are not designed to clean the edge of the semiconductor wafer, as opposed to the major flat surface which has been polished. Without assuring that wafer edges will be cleaned, downstream operations in the semiconductor fabrication process may become contaminated with particles riding on the wafer edges. As a consequence, it is desirable to create a cleaning tool which also removes particulate matter from the edge of the semiconductor wafer.